Enzymatic synthesis of gentiooligosaccharides by transglycosylation with beta-glycosidases from Penicillium multicolor.

A crude enzyme preparation from Penicillium multicolor efficiently produced mainly gentiotriose to gentiopentaose (d.p. 3-5) by transglycosylation using a high concentration of gentiobiose as the substrate. The resulting gentiotriose was examined in a gustatory sensation test using human volunteers, and was determined to have one-fifth of the bitterness of gentiobiose. The crude enzyme preparation was analyzed by chromatography to determine the enzyme responsible for formation of the gentiooligosaccharides. The transglycosylation was shown to take place in two stages by a combination of beta-glucosidase and beta-(1-->6)-glucanase. In the initial stage, which was the rate-limiting step in the overall process, beta-glucosidase produced mainly gentiotriose from gentiobiose. In the second step, beta-(1-->6)-glucanase acted on the resulting gentiotriose, which served as both donor and acceptor, to produce a series of gentiooligosaccharides (d.p. 4-9) by transglycosylation.